The present invention generally relates to a telecommunication network coupled to a serving network of an Internet Service Provider (ISP) for carrying out the authentication, authorization and accounting of remote-access users. More particularly, the invention pertains to means, system and method for enabling networks of the above type to determine the appropriate Authentication, Authorization and Accounting server (hereinafter referred to as an AAA-server) in charge of a user having issued a service request.
The access to Internet services is nowadays given by an ISP. In the most general scenario, different operators manage the ISP network and the access network. Both networks are thus considered separate networks. The ISP performs authentication, authorization and accounting checks on users accessing its services via an access network. In particular, these users are subscribers of a telecommunication network acting as an access network to the ISP network.
Thus, when a user of a telecommunication network wishes to connect with a certain server that belongs to an ISP, a service request is sent from the user to said ISP server via a Network Access Server (NAS), which belongs to the telecommunication network. Nevertheless, said user must be previously authenticated and said service request must be previously authorized by an entity such as an Authentication, Authorization and Accounting server (AAA-server). To this end, when the user sends a service request toward the NAS he also enters a user identifier and a password for his own identification. This information is sent toward the AAA-server using a communication protocol such as the Remote Authentication Dial In User Service (generally known as RADIUS), or the RADIUS upgrading known as DIAMETER protocol, or the like.
The Internet Engineering Task Force (IETF) defines the RADIUS protocol in RFC 2865. Likewise, the DIAMETER protocol is defined in “draft-ietf-aaa-diameter-08.txt” which is also driven by IETF. The basic concept behind DIAMETER is to provide a base protocol that can be extended in order to provide AAA-services for new access-related technologies. Both RADIUS and DIAMETER specifications describe protocols suitable for carrying out the authentication and authorization as well as for collecting the accounting information between the NAS and the AAA-server where the NAS desires to authenticate its links.
Provided that the protocol used is RADIUS, when a NAS operating as a client of a RADIUS AAA-server receives an incoming service request, said NAS obtains identification information from the user, namely a Name and a Password, and then issues an authentication request to the RADIUS AAA-server. The RADIUS AAA-server, upon receiving the identification information and other NAS information, authenticates the user. That is, depending on who the user is, he is authorized to have access to different services and possibilities. The RADIUS attributes carry the specific authentication and authorization data as well as information and configuration details for the request and reply packets.
For instance, attributes that can be carried in these packets are the User-Name, User-Password, and others. In particular, the attribute User-Name indicates the name of the user to be authenticated. The format of this User-Name in the RADIUS protocol may be one of several forms:                Text, a form consisting only of UTF-8 encoded characters        Network Access Identifier (NAI), namely username@realm, as described in RFC 2486        Distinguished Name (DN), which is a name in ASN.1 form used in Public Key authentication systems        
On the other hand, when DIAMETER is the protocol used, the procedure is similar to the previous case. A NAS acting as a client of a DIAMETER AAA-server initiates a request for authentication and/or authorization of a given user towards said DIAMETER AAA-server. The DIAMETER AAA-server, upon receiving the identification information and other NAS information, authenticates the user. That is, depending on who the user is, he is authorized to have access to different services and possibilities.
Any data transferred by the DIAMETER protocol is in the form of an Attribute Value Pear (hereinafter AVP). Said AVP is used by the base DIAMETER protocol, among other things, for transporting the user authentication information towards the DIAMETER AAA-server. The user name is provided in the User-Name AVP, which allows an NAI format, or in a UTF-8 format consistent with the NAI specification.
A typical scenario of a telecommunication network coupled to an ISP for providing Internet services is the provision of Internet access in a General Packet Radio Service (GPRS) network. In this scenario, a Gateway GPRS Support Node (hereinafter GGSN) may inter-work with an AAA-server typically using RADIUS protocol. Thus, a GGSN acts as a client of a RADIUS AAA-server.
Another scenario is a Wireless Local Area Network (WLAN) accessing Internet through a WLAN Access Point connected to an AAA-server by means of DIAMETER or RADIUS protocols. Thus, a WLAN Access Point may respectively act as a client of a DIAMETER AAA-server, or as a client of a RADIUS AAA-server.
Nowadays, the ISPs store user information for all its users in large backend databases, namely AAA-servers, which the AAA-client may access to. In scenarios where the number of users is very high, this solution is not easily scalable as the size of the databases and the number of queries per second necessarily decrease the network performance. In particular, provided that each ISP has organized its users in a unique large AAA-server, a direct relation between said AAA-server and the requester AAA-client must be maintained during the complete session what, in the case of accounting related transactions, may penalize the expected AAA-server performance.
An immediate solution for an ISP having a very high number of users may be that the ISP needs more than one AAA-server to organize its user information. A first disadvantage of this multiple AAA-server frame is that the security relations between the AAA-client and the different AAA-server become more complicated. A second disadvantage is that the ISP network structure becomes more visible to the AAA-client, which may be a NAS operated by another operator, and thus produces network configuration dependencies between the ISP and the operator of the telecommunication network.
Independently of the disadvantages above, the AAA-clients requesting service from an ISP having a plurality of AAA-servers need to know what AAA-server should be contacted for a particular service request of a certain user. In the absence of other criteria, an AAA-client might perform sequential queries to those AAA-servers of a coupled ISP until finding the appropriate AAA-server in charge of a certain user.
Better performances than for sequential queries may be achieved by interposing an AAA-proxy between the AAA-client and an ISP network having a plurality of AAA-servers. Such AAA-proxy is typically able to differentiate between AAA-servers on a per domain basis. Thus, by making use of user identifiers in a NAI format or likewise, namely username@realm, an ISP may dispose its users amongst different AAA-servers on a per realm basis. The AAA-proxy above is then able to determine the specific AAA-server in charge of all users in a specific domain, namely the domain addressed by the realm shared by such users.
Currently, there is no other criterion for disposing users amongst AAA-servers in an ISP network. In this respect, just the well-known and structured realm in a NAI format above, for example “acme.com”, may be used to unambiguously determine a unique AAA-server responsible for a certain domain in an ISP network.
However, there are User-Name formats other than NAI, or not consistently structured, or even unstructured, for which such an AAA-proxy is not able to distinguish among a plurality of AAA-servers and this is a major drawback for the ISPs. For instance, an AAA-proxy receiving service requests from a GGSN acting as a NAS of a GPRS network, the GGSN making use of the Mobile Subscriber ISDN number (MSISDN) as user identifier, is not able to select one of a plurality of AAA-servers for this sort of user identifier.
Moreover, and even for User-Names in NAI formats, said AAA-proxy is not able to distinguish more than one AAA-server for the same domain. That is, all the users given the same realm in a NAI format must be located in the same AAA-server in a certain ISP network. This unique disposition of all users with the same domain or realm in the same AAA-server is still considered a drawback for the ISPs, since more complicated mechanisms for load balancing between AAA-servers of different capacity should be introduced.
A further drawback, where User-Name formats do not include a realm or domain identifier, is that the inclusion of the aforementioned AAA-proxy as such does not solve the identification of a unique AAA-server in charge of a certain user in an ISP network having a plurality of AAA-servers. In this respect, operators of a telecommunication network, where subscriber identifiers do not include a realm or domain identifier, might see this AAA-proxy as a superfluous entity penalizing the AAA-service performance. However, the introduction of this AAA-proxy may overcome, or at least minimizes the two aforementioned disadvantages, security relations and visibility of ISP network structure, especially when the AAA-proxy belongs to the ISP network. In this particular case, the inclusion of such an AAA-proxy benefits the ISP interest whereas penalizes operators of telecommunication networks of this type above.
Thereby, it is a first object of the present invention to provide the means and methods for disposing users of AAA-services amongst a plurality of AAA-servers independently from user identifier schemes, structures and applicable service.
It is a further object of the present invention to make compatible the first object above with the inclusion of an upgraded AAA-proxy in order to solve said first and second disadvantages above, those related to security relations and visibility of ISP network structure. Said upgraded AAA-proxy being able to select the appropriate AAA-server in charge of a given user independently from user identifier schemes, structures and applicable service, thus accomplishing the first object of the present invention.
An interesting start point is found in typical wireless systems of 2nd generation like GSM and ANSI-41 networks. As said wireless systems were getting more and more subscribers, the operators wanted high dimensioned subscriber databases like the Home Location Register (HLR) in order to hold a huge amount of subscriptions, minimizing the O&M activities, and optimizing the routing tables in the Signalling System number 7 (SS7) network. The more recent appearance of Number Portability requirements, in some cases by law regulation, where individual subscribers were moved from one HLR belonging to one operator to another HLR belonging to another operator definitely made the needs for a database selector being a must.
An exemplary description of such a database selector can be found in the international application WO 99/23838 wherein said database selector in a certain network is referred to as Flexible Number Register (FNR). This FNR is the natural entry point in a wireless network of 2nd generation for queries related to those subscribers whose user number series belong to said network independently of what network currently holds the subscriber subscription. That is, said FNR comprises all the user number series addressing such network and also individual user numbers for subscribers ported into this network from another network. Besides, individual user numbers of home subscribers who had been ported to another network are specially marked and have a particular network identifier to reach an entry node in the network where the subscriber currently holds his or her subscription.
Subscriber related queries based on user numbers such IMSI or E.164 formats are addressed to the FNR in a network addressed by said IMSI or E.164 format. These formats correspond to well-structured number series of a predefined length. Then, the FNR determines whether the query should be simply transferred to the appropriate HLR within its own network for subscribers never ported or imported from other networks, or the query should be re-directed to the appropriate network where the subscriber has been exported. All the required routing and addressing mechanisms are carried out at lower signalling layers like at the Signalling Connection Control Part (SCCP) within SS7.
Even though this solution is considered a relevant prior art, it still presents serious limitations for a direct applicability to newer scenarios interconnecting traditional fixed and wireless telephony networks with Internet and Multimedia service networks in large telecommunication systems. For example, this FNR prior art just considers signalling, routing, and addressing in accordance with SS7 principles where subscriber or user identifiers are merely based on structured numbers. Moreover, at least one of the identifiers associated to a subscriber must be structured in such a way that the analysis of such number unambiguously identifies the appropriate HLR. Still another limitation of this previous solution is that neither other newer identifier realms, nor protocol support other than SS7 related upper layers were considered during the development of these 2nd generation wireless networks. Further, there is nothing anticipated in this prior art in respect of service-dedicated servers, such as those related to AAA-services, that must be addressed in response to queries based on corresponding user identifiers.
Thereby, the aforementioned objects of the present invention do not seem to be accomplished or anticipated by the teachings from the application above. In this respect, the provision of means and method for allowing a balanced disposition of users amongst a plurality of AAA-servers independently from user identifier schemes, structures and applicable service is still an object of the present invention. Said means and method, compatible with the introduction of an AAA-proxy between the AAA-client and an ISP having a plurality of AAA-servers for supporting said balanced disposition of users, is still another object of the present invention.